Only verbs can add "ing". "off" is not a verb, so you can't make a verb form like "offing". "don't bother" is not followed by "of", by the way.
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Nona The BritAction is increasingly used as a verb in business jargon (yuk and I hate it).
Convention apparently now allows for the use of 'grow' as we have always used it as in 'grow daffodils in the front yard'. On radio ads recently: 'if you want to grow your business, meaning to increase it, 'make it grow'.